don't crash if DB is unavailable

src/index.js

@@ -1,112 +1,110 @@
-require('dotenv').config()
-var process = require('process')
-const express = require('express')
-var CronJob = require('cron').CronJob;
-const etherscan = require('./etherscan');
-const AppError = require('./error');
-const prom = require('./prometheus');
-const DB = require('./db');
+require("dotenv").config();
+var process = require("process");
+const express = require("express");
+var CronJob = require("cron").CronJob;
+const etherscan = require("./etherscan");
+const AppError = require("./error");
+const prom = require("./prometheus");
+const DB = require("./db");
 
 const startServer = () => {
-    const server = express();
+  const server = express();
 
-    server.get('/metrics', async (req, res) => {
-        try {
-            res.set('Content-Type', prom.register.contentType)
-            res.end(await prom.register.metrics())
-        } catch (ex) {
-            res.status(500).end(ex)
-        }
-    });
+  server.get("/metrics", async (req, res) => {
+    try {
+      res.set("Content-Type", prom.register.contentType);
+      res.end(await prom.register.metrics());
+    } catch (ex) {
+      res.status(500).end(ex);
+    }
+  });
 
-    const serverPort = process.env.SERVER_PORT || 3000;
-    const serverHost = process.env.SERVER_HOST || '127.0.0.1';
-    server.listen(serverPort, serverHost, () => console.log(`Http server running on port ${serverHost}:${serverPort}`));
-}
+  const serverPort = process.env.SERVER_PORT || 3000;
+  const serverHost = process.env.SERVER_HOST || "127.0.0.1";
+  server.listen(serverPort, serverHost, () => console.log(`Http server running on port ${serverHost}:${serverPort}`));
+};
 
 let dbStateDiff;
 
 const connectToDB = () => {
+  try {
     const statediffUser = process.env.STATEDIFF_PG_USER;
     const statediffPassword = process.env.STATEDIFF_PG_PASSWORD;
     const statediffDB = process.env.STATEDIFF_PG_DATABASE;
     const statediffHost = process.env.STATEDIFF_PG_HOST;
     const statediffPort = process.env.STATEDIFF_PG_PORT;
-
-    dbStateDiff = new DB('statediff', statediffUser, statediffPassword, statediffDB, statediffHost, statediffPort)
-}
+    dbStateDiff = new DB("statediff", statediffUser, statediffPassword, statediffDB, statediffHost, statediffPort);
+  } catch (error) {
+    console.error("db connection error", error);
+  }
+};
 
 const run = async () => {
+  // statediff database
+  const dbStateDiffBlockNumber = dbStateDiff.getBlockNumber();
 
-    // statediff database
-    const dbStateDiffBlockNumber = dbStateDiff.getBlockNumber();
+  // Etherscan
+  const etherscanBlock = etherscan.getBlockNumber();
 
-    // Etherscan
-    const etherscanBlock = etherscan.getBlockNumber();
+  const results = await Promise.allSettled([etherscanBlock, dbStateDiffBlockNumber]);
 
-    const results = await Promise.allSettled([
-        etherscanBlock,
-        dbStateDiffBlockNumber,
+  for (const result of results) {
+    if (result.status === "rejected") {
+      if (result.reason instanceof AppError) {
+        const errorData = result.reason.data;
+        console.log(errorData.type, errorData.message);
+      } else {
+        console.error(result.reason);
+      }
+    } else if (result.status === "fulfilled") {
+      const value = result.value;
+      switch (value.type) {
+        case "etherscan":
+          prom.etherscanGauge.set(value.blockNumber);
 
-    ])
+          break;
+        case "statediff":
+          prom.statediffDBGauge.set(value.blockNumber);
 
-    for (const result of results) {
-        if (result.status === 'rejected') {
-            if (result.reason instanceof AppError) {
-                const errorData = result.reason.data;
-                console.log(errorData.type, errorData.message);
-            } else {
-                console.error(result.reason);
-            }
-        } else if (result.status === 'fulfilled') {
-            const value = result.value;
-            switch (value.type) {
-                case 'etherscan':
-                    prom.etherscanGauge.set(value.blockNumber);
-
-                    break;
-                case 'statediff':
-                    prom.statediffDBGauge.set(value.blockNumber);
-
-                    break;
-            }
-        }
+          break;
+      }
     }
-}
+  }
+};
 
-const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));
+const sleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms));
 
 const main = async () => {
-    startServer();
-    connectToDB();
+  startServer();
+  connectToDB();
 
-    let lock = false;
+  let lock = false;
 
-    var job = new CronJob(
-        '*/10 * * * * *',
-        async () => {
-            if (lock) {
-                console.log('Parallel process is executing. Skipping');
-                return;
-            }
-            lock = true;
+  var job = new CronJob(
+    "*/10 * * * * *",
+    async () => {
+      if (lock) {
+        console.log("Parallel process is executing. Skipping");
+        return;
+      }
+      lock = true;
 
-            try {
-                await run();
-            } catch (e) {
-                console.error(e);
-            }
+      try {
+        await run();
+      } catch (e) {
+        console.error(e);
+      }
 
-            lock = false;
-        },
-        null,
-        true
-    );
-}
+      lock = false;
+    },
+    null,
+    true
+  );
+};
 
 main().catch((e) => console.error(e));
 
-process.on('SIGINT', () => {
-    console.info("Interrupted")
-    process.exit(0)
-})
+process.on("SIGINT", () => {
+  console.info("Interrupted");
+  process.exit(0);
+});